DESCRIPTION: The central hypothesis of the proposal is that PLDs are important regulators of cell biological processes. More specifically, the P.I. proposes that PLD1 regulates secretion in response to stimulation and that PLD2 plays a role in receptor-mediated recycling or secretion. The specific aims address the central hypothesis. Aims 1 and 3 deal mainly with the molecular biology, enzymology, and activation of the PLDs, while Aims 2 and 4 deal more directly with the functions of the PLDs.